Conveyor assemblies for vehicles, such as automobiles and the like, are used in car washes and other applications to move the vehicle across a horizontal surface. A track extends along the horizontal surface. On demand, a dolly may rise out of an opening at an entrance end of the conveyor assembly to engage a tire of the vehicle. The dolly is driven by a chain to advance the vehicle along the conveyor until the vehicle exits and the dolly drops below the horizontal surface to eventually return to the entrance end of the conveyor. The dollies have two alternative paths relative to the track. One path is below the horizontal surface, where the dolly is out of the way while still being advanced by the chain, when a vehicle is not present to be moved along the track. The other path is above the horizontal surface, where the dolly is capable of moving the vehicle as the chain advances.